1640997 has 6 divisors (see below), whose sum is σ = 2370342. Its totient is φ = 1093992.

The previous prime is 1640971. The next prime is 1641007. The reversal of 1640997 is 7990461.

1640997 is a `hidden beast` number, since 1 + 640 + 9 + 9 + 7 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1640961 + 36 = 1281^2 + 6^2 .

It is not a de Polignac number, because 1640997 - 2⁷ = 1640869 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640927) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 91158 + ... + 91175.

It is an arithmetic number, because the mean of its divisors is an integer number (395057).

2^1640997 is an apocalyptic number.

It is an amenable number.

1640997 is a deficient number, since it is larger than the sum of its proper divisors (729345).

1640997 is a wasteful number, since it uses less digits than its factorization.

1640997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182339 (or 182336 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 1640997 is about 1281.0140514452. The cubic root of 1640997 is about 117.9512630294.

Subtracting from 1640997 its sum of digits (36), we obtain a square (1640961 = 1281²).

The spelling of 1640997 in words is "one million, six hundred forty thousand, nine hundred ninety-seven".